SAE - American Acronym that represents the name of the Institution (Society of Automotive Engineers) Society of Automotive Engineers - Classifies lubricants by viscosity ranges in two scales: a low temperature one (0W, 5W, 15W) where the letter W means Winter ( winter) and another of high temperature (30, 40, 50).
It is also important to know that since its emergence at the beginning of the last century, SAE has determined worldwide standards for automotive lubricant viscosity.